1. Field of the Invention
The present invention relates to an improved separation system for separating aluminum based materials from heavier materials. More particularly, the invention involves use of an air header which separates heavier materials from lighter, aluminum-based materials based upon the weight of the materials.
2. Background Information and Description of the Prior Art
Recycling of waste materials has recently become of the utmost importance in environmental protection measures. The decrease in available landfill space has made recycling the primary solid waste management option. In addition, in the packaging and container fields, such as in the used beverage container field, recycling of and reclaiming aluminum components from used beverage and other food cans is becoming more economically attractive.
Methods for separating various aluminum alloys from materials have been known. For example, methods are provided which can separate alloys used for can ends or lids from a different aluminum alloy used for the body of a can. However, prior to separation of the aluminum alloys in accordance with such methods, it is necessary to separate out non-aluminum components such as lead and other unwanted materials from the used can stream. Magnetic separators have been known and employed for removing magnetic metal, but heretofore nothing has been known for successfully removing non-magnetic materials.
The non-magnetic materials can present a substantial problem. For example, persons who bring used food and beverage aluminum cans to a recycling station are often compensated for doing so based upon the weight of the amount of materials which they submit for recycling. It has become an increasing problem that cans are contaminated with materials such as dirt, lead, sand or other waste products. In addition, some materials have been found to have been placed in used cans by persons who submit the material for recycling in order to provide a greater weight to the overall batch of cans. The items found have included rocks, glass, wood and lead. It has been determined that a substantial percentage of used food and beverage can material is contaminated with these materials because large percentages of non-aluminum substances such as silica and lead have been detected in the material when it is melted in preparation for recycling.
It has been known to provide methods of delacquering and then separating metallic components from used food and beverage cans. For example, U.S. Pat. Nos. 4,468,847 and 4,592,511, both of which are owned by the assignee of the present invention, involve a temperature separation process. This process includes inducing fragmentation of aluminum cans and then separating the fragmented pieces based on the aluminum alloy of each piece. Temperature separation processes are based upon initiation of incipient melting which occurs at different temperature values depending upon different alloys present. Furnaces for accomplishing such temperature-based separation are described in U.S. Pat. Nos. 4,491,473 and 4,498,523 both of which are owned by the assignee of the present invention. As mentioned hereinbefore, however, such systems relate to separation of various aluminum alloys which are contained within food and beverage containers. These disclosures do not relate to separating non-aluminum components from a stream of used food and beverage cans.
Other methods of separating and sorting various materials have been known. For example, U.S. Pat. No. 3,011,634 discloses a method and apparatus for sorting materials such as uranium ore and gold ore. This separation technique is based upon radioactivity detected in the ore. For example, uranium ore will emit a radioactive signal which is detected and a suitable device is then used to remove or separate the uranium ore from the stream. In accordance with one aspect of this disclosure, an air blast can be initiated to remove or separate out the uranium ore from the stream.
Another disclosure relating to sorting pieces of ore in accordance with mineral value is disclosed in U.S. Pat. No. 3,075,641. This patent involves measuring of the size of pieces of ore falling through a detector. The size is determined based upon the effect the moving fragment has when it passes between a stationary light detector and a second detector.
U.S. Pat. No. 3,216,567 discloses a method of sorting rock materials which have different electrical resistances associated with each rock fragment. The property of electrical resistance is utilized for mechanical sorting. A blast of air is used to remove or deflect fragments which do not have the desired set of electrical characteristics.
Other methods have been known for sorting various materials. For example, U.S. Pat. No. 3,917,567 discloses an air classifier for shredded refuse in which the shredded material is sorted on a weight-versus-surface area basis. The disclosure involves a series of ten vertical columns through which the material correspondingly passes and a sorting action takes place in the columns when vertically rising air, being at a lower velocity in each succeeding column, lifts succeedingly lighter portions of the shredded refuse onto the next column while heavier portions rest on the bottom and can be removed.
U.S. Pat. No. 4,127,476 discloses an air classification apparatus for segregating mixed office paper waste. An air source is placed at the bottom of a column which lifts pieces of shredded material upward. Lower pressure air jets are injected at various places through the column to direct medium and light fractions of the shredded material into separate collection hoppers.
U.S. Pat. No. 3,738,483 discloses a method and apparatus for classifying shredded refuse material such as household waste, grass clippings, and the like. The material to be classified is dropped or projected so as to fall into a chamber. Air may be blown into the airborne material as it falls to assist in separating the material into various classifications. With this device and method, the air stream must be sufficient so as to overcome the downward velocity of the falling materials caused by the acceleration of gravity.
A classifier for particulate material is disclosed in U.S. Pat. No. 3,933,626. This classifier involves a stream of particles being introduced into a moving stream of air and the classification is achieved by the varying degrees of entrainment of the particles in the air stream due to their difference in size.
A method and apparatus for separating a tobacco mixture into lighter and heavier fractions is disclosed in U.S. Pat. No. 4,475,562. This disclosure involves a tobacco leaf mixture which contains lighter and heavier fractions being fed into one side of a housing while an air stream flow is introduced at the other side. A suction lift is maintained at the top of the housing to increase the velocity of lighter fractions. Lighter fractions are then siphoned off and these lighter fractions are used as the material from which shredded cigarette tobacco filler is made.
These disclosures do not disclose the separation of aluminum-based materials from heavier scrap metal or non-metallic items from a used food and beverage can stream. There remains a need for a simple, economical and efficient method of separating aluminum components from non-aluminum components in the used beverage can stream. This need exists with particular importance with respect to non-magnetic materials which cannot be separated by known magnetic separation techniques.